This application is based on and claims the benefit of German Patent Application No. 10138728.8 filed Aug. 7, 2001, which is incorporated by reference herein.
The invention relates to a coupling element for mounting to a shielded electrical cable comprising at least two insulated electrical conductors, a flexible metallic shield surrounding it, and a jacket made of an insulating material placed on top thereof. The shield is fixed to a sleeve-like metallic adapter into which project the insulated electrical conductors of the cable. Contact elements arranged in a contact carrier made of a mechanically stable insulating material are fixed to the conductors. The adapter is surrounded by a protective part made of an insulating material produced by injection molding and projecting over the cable while leaving free the adapter opening that faces away from the cable. The invention further relates to a method for mounting the coupling element to a cable, e.g., of the type described in German Patent Application DE 30 34 415 A1.
A coupling element in terms of the invention can be a connector or a socket. The associated contact elements can be configured as pins or as jacks. Shielded electrical cables are used, for instance, in portable radio equipment, as telephone lines, in spring cables for fixed electroacoustic systems, or in vehicles, ships, aircraft, and especially in railroads. The coupling elements should be moisture-tight per se. Their connection with the respective cable must also be moisture-tight. In addition, the shield of the cable must be connected to the coupling element without any gap.
In the prior-art coupling element disclosed in the above-mentioned document DE 30 34 415 A1, the cable-side end of a metallic adapter is embodied as an attachment whose radial dimensions are smaller than the dimensions of a grip section of the adapter on the connection side. A circumferential groove-like indentation is made in the attachment at a distance from its cable-side end. The attachment furthermore has at least one axially extending recess running from the cable-side end up to the indentation for receiving a tension member of the cable, which is guided up to and into the indentation. The attachment is moreover provided with a metallic sleeve that projects over the cable and firmly fits against the attachment. This sleeve also covers the shield of the cable connected to the attachment. A grip element made of an insulating material is injection-molded around the cable-side end of the basic body and the end of the cable. This coupling element is attached to the end of the cable such that it securely contacts the shield and is moisture-tight. However, it cannot be removed from the cable end without being destroyed. To correct any errors and to change the positions of the contact elements in the coupling part, said coupling part must therefore be newly mounted each time.
An object of the invention is to design the initially described coupling element and the associated method so that it can be detached, while maintaining its moisture-tight arrangement on the cable and the non-interrupted shielding.
According to the invention, this object is attained by
the adapter being provided with a hollow space, which is free from the insulation material of the protective part and serves to receive reserve lengths of the conductors, and
a metallic sleeve provided with an internal thread and freely rotatable about its axis being captively attached to the adapter at the adapter end facing away from the cable and encompassing said adapter, and a connector body equipped with a threaded fitting and encompassing the contact carrier being screwed into said sleeve so that it abuts the adapter with a moisture-tight fit.
The hollow space for receiving the reserve lengths of the conductors is produced by a cover, which encloses the conductors during injection molding of the protective part and which fits against the wall of the adapter.
The coupling element is made moisture-tight and is jointed to the cable by the protective part that is injection-molded around it. It can nevertheless be removed without risk of damage because the connector body can be detached from the adapter by means of the sleeve. The conductors of the cable, which are actually too long when the coupling element is assembled, are received as reserve lengths in the hollow space of the adapter where they are protected against damage. When the coupling element is opened, these reserve lengths of the conductors allow problem-free handling of the conductors with the contact elements attached thereto. The coupling element can therefore be opened at any time if required, making it possible, for instance, to change the positions of the contact elements in the contact carrier. For this purpose, only the metallic sleeve needs to be rotated so that the connector body is removed therefrom. The contact carrier is then ready for any type of manipulation. Thus, it is also possible to conduct measurements for troubleshooting. Subsequently, the connector body with the contact carrier is screwed back into the sleeve by rotating the sleeve. The contact carrier is not rotated to close or open the coupling element. It is only moved in an axial direction. Thus, the connected conductors are not twisted but are only pushed together in axial direction to form the reserve lengths or pulled apart again.